Vermiculite ore treatment



Dec. 6, 1938,. R. ERICSON VERMICULITE ORE TREATMENT Filed April 5, 19562 Sheets-Sheet l Q NH mm MN Q [fa/6722b?- Ric/2am! lrwaon,

T R. ERICSON VERMICULITE ORE TREATMENT Dec. 6, 1938.

Filed April 5 1936 2 Sheets-Sheet 2 Patented Dec. 6, 1938 PATENT"OFFICE,

v 2,139,358 mnmcmm one TREATMENT,

Richard'Ei-icson, Chicago, 111., assignor to Universal-InsulationCompany, Chicago, 111., a corporation of Illinois Application April s,1936, Serial No. 12,530,

. 7 Claims.

The present invention relates to a. procedure and apparatus for dealingwith mine-run vermiculite or analogous ore whereby to prepare it forfurther use, particularly for expansion by the 5 process described inUnited States Letters Patent 1,963,276 or by a similar procedure, andthe method is based upon certain physical characteristics of thevermiculite and the associated rock impurities described hereinafter.

l One of the principal objects of the invention is to segregate thevaluable vermiculitefrom its gangue, a further purpose of the inventionbeing to break down the larger vermiculite flakes, that are too bulky orof too great size ,for proper l expansion, into smaller flakes and tograde the latter so produced to a maximum thickness limit.

Another aim of the invention is to breakdown lumps of vermiculite andimpurities into their components, an additional object being to process20 wet or damp ore and to provide means by which the vermiculite may bedried.-

vermiculite, which is sometimes referred to as hydrated biotite mica,has the unique property of expoliating or expanding into many times its25 original volume when properly heated, the product so formed havingheretofore been used to advantage as a heat-insulating materialas wellas for an aggregate associated with cementitious agents.

The vermiculite as found in nature is often associated with rockimpurities which in the past have been difficult to remove.

In certain natural deposits these impurities are principally pyroxeniteand syenite, and these 35 sometimes comprise as much as 67% by weight ofthe entire mass and they are well dispersed throughout the vermiculite,and, in fact, not infrequently the vermiculite is superficially attachedto particles of impurities, and, in other 40 cases, particles ofvermiculite and impurities are intermingled or interspersed, forminglumps or conglomerates, and the ore is often in a wet or damp conditiondue to ground water and to atmospheric conditions.

By the present invention this lumpy, damp, comparatively-lean mixture ofvermiculite and foreign matter may be made into dry, graded flakes ofvermiculite, containing less than 7% impurities, which are very welladapted for ex- 50 pansion by the process disclosed in the United Statespatent referred to,

One method now in use consists in passing the mine-run ore overrevolving grizzles to remove the larger lumps, the material passingthrough 55 the grizzles being screened on a vibrating-screen havingopenings between one-quarter inch square and No. 10 mesh, somediillculty having been experienced in screening wet ore through a No. 10

screen. The oversize retained on the %,-inch screen isground in aswing-hammer mill and re- 5 circulated until all of it passes throughthe quarter-inch openings, such sized ore being then treated on aSutton, Steele and Steele air-table which separatesthe vermiculite fromthe impurities, such segregation not being complete, as usually over ofthe apparently-clean vermiculite constitutes impurities. Itis sometimesfound of advantage to'separate the minus quarter-inch plus .IO-meshsized oreinto' two sizes before cleaning on the ai'r-tables, The ore isnot dry except whenclimatic conditions dry itnat- Qurally. The damp,seemingly-clean,- vermiculite is then shipped to the expanding plant-forfurther treatment, and an examination of the'flakes will show that someare as much as 0.075 inch in thickness, thisbeing too thick 'forproperexfoliation by the process-referred to.

By thevpro cedure followed in accordance with this. newlnvention,however, it is possible to workdamp ore and to remove-the impuritiesfrom the vermiculite and at the 'saui e'ti'me to disintegrate theflakesi'rito thinner ones graded to a suitable maximum-thickness limit.A mixture of thick and thin vermiculite flakes is not uniformly expandedor exfoliated by any of the commonly used methods of expansion, because,if sufflcient heat be used to expand the thicker flakes properly, thethinner flakes will be overheated, and. consequently, there is a maximumlimit for thickness which should not be materially exceeded to obtaindesirable exfoliation of all the particles undergoing treatment.

As explained hereinafter, all of the abovenoted operations can beeffected in one apparatus, although other types of appliances that willrequire various steps may be employed and still be within the scope ofthe invention. The material can also be dried during the processing.

The new process takes advantage of the difference in shape anddisintegration'properties of the impurities and of the vermiculite, theparticles of vermiculite being flat and comparatively thin in onedimension, while the particles of impurities tend to have a spherical orcubical shape with all dimensions about the same.

When vermiculite particles are disintegrated, especially by beingsubjected to a shearing action parallel to the planes of cleavage, thelarge flakes are broken upor disassociated into thinner ones which oftenhave the same area of the flat side 55 as the original particle,thisiiaking or dissevering being considerably facilitated if theparticles are moistened.

The pieces of impurities, however, when subjected to a shearing,crushing orimpact blow are disintegrated "into fragments which are 'of"ageneral spherical or cubical nature and have comparatively all of theirdimensions the same.

If the particles of vermiculite and impurities are disintegrated to passthrough slotted openings which are just sufiiciently-wide to permit.the.pas sage of the vermiculite flakes edgewise by the shortestdimension, and then passed "over a square-opening screen, the widestldimensions of which are equal to, or preferably larger than, the widthof the slot, then a separation or segregation of the flake-likevermiculite from the cube-like impurities take place. The vermiculiteflakes, scales or plates, because of their much greater lengththan theirwidth, will be caught and retained on, the screen while the impurities,

having all dimensions more or less the same, and one of whichissuiiici'ently short to pass the slot; will pass through thescreen, and,in practice, it has been found'thatthe jagged inequalities of the impureparticlesfwill necessitate the inside dimension of the square openingsof thescreen being appreciablyflarger, about 70% to 90%.

thanthe width or thefslbt; The vermiculite that may have passed through'the. square screen with the impurities can be recovered by'subsequentaidedby the-fact that they'do ,not disintegrate as quickly-as thevermiculite.

To enable. those a'cquaintedwith this art to fullyunderstandthe presentinvention and the several advantages and benefits accruing from itsadoption a present preferred machine embodiment of theinvention has beenillustrated in the accompanying drawingsforming a part of thisspecification and to which reference should be had in connection withthefollowing detailed description, and, for simplicity, like referencenumerals have been employed throughout the several views of the drawingsto designate the same. parts.

In these drawings:--

Figure 1 is a substantially-central, longitudinal, vertical sectionthrough the apparatus, with parts more or less broken away;

Figure 2 is an elevation of the right-hand end of the appliance;

Figure 3 is a vertical cross-section on line 3-3 l of Figure 1;

Figure 4 .is an enlarged, fragmentary cross section through the lowerportion of the multiple revolving drum, showing the three types ofscreens, used, and illustrating also one of the several cylindricalgrindingerods; and Figure 5 is a fragmentary cross-section through themiddleslotted drum on a still larger scale.

This apparatus comprises an inclined, multiple, revolving drum ortrommel, characterized as a whole ll, having around its periphery three,concentric drums l2, l3, and H, the inner one of which is formed of anumber of longitudinal,

parallel, solid, wear-resisting, metal bars l5, l5 which are of theshape in cross-section shown in Figure 4 and which indicates that oneside of each of these bars is formed so that any material notsufl'icientlp reduced in sizewill be carried up to the top of 'the drumand then dropped down.

In the present preferred embodiment of the invention these bars [5, l5are spaced apart three-quarters of an inch at their closest points which'is'sufilciently far apart to permit the properly-reduced materialwithin the drum to pass to the second orgnextouter drum. As is fullyshown,

the spaces between these bars enlarge downward- 1y or outwardly and thespaces are at an angle to 'the'correspon'ding radius of the drum,whereby any material which can pass through the narrowest inner portionsof such slots will encounter -no substantial restriction therebelow.

- This inner drumor grating accommodates a number of loose, solid-metalgrinding-rods l6, is of substantially the length of the drum and bearingon its inner surface, these grinding-rods during the rotation of thedrum assuming positions somewhat analogousto those indicated in Figure3, such rods acting during the revolution of the drum to provide ashearing action on the particles (if-vermiculite substantially parallelto the planes of the flakes of which they are made 'ii ana also to applya grinding force to the parti'cles of impurities.

The second or next outer drum I3 comprises a slotted grill made up of alarge number of parallel rods ll, 11 of the shape in cross-section asshown in Figure 5, being somewhat of inverted -V -shape o'n'top withnarrow slots l8 between their upper portions, the spaces I9 outwardly be'yond such narrow slots diverging or flaring outwardly as is fullydepicted; whereby the crosssection of these metal bars l1 forming theslots l8- l9 is such as to prevent binding of the vermiculite' fiakeswhich tend to pass therethrough,

these screens belngsoldin the trade under the name Rima.

The width of each slot 18 in the present device is .04 inch and suchslots may beof any length greater than one-half inch.

It is also possible to use slots formed by perforated metal plates forthis drum, and in general the greater the percentage of openings, thegreater the capacity of the drum, but the area of openings must bebalanced against wear and service.

The outer drum l4 consists of a woven-wire metal-screen having openings0.078 inch square.

These several drums are mounted in the relation stated by any convenientstructural means, the triple drum being supported for rotation in anyappropriate manner, as by resting on flanged rollers 2i cooperating withend rings 22 of the multiple drum resting upon them.

At one end the compound drum is provided with a ring-gear 23 in meshwith a driving-pinion 24 on the shaft of reduction-gearing 25 driven byan electric-motor 26, all of these features being of the usual type forrevolving drums.

At its more elevated end the drum is closed by a wall 21 through whichan inclined chute 28 extends a slight distance into the drum and theother, or lower, end of the drum is closed by a wall 29 through anopening in which an inclined, reciprocating, slotted screen,characterized as a whole 3|, extends.

As is shown in Figure 3, that portion of this screen 3| inside of themultiple drum has flaring or diverging side-walls 32, 32, the screenitself being divided into two parts, upper and lower, 33 and 34,respectively, each screen section being composed of parallel bars spacedapart, those of the section 33 having slots one-half inch wide, whilethose in the section 34 are one-quarter inch wide.

The duplex -or multiple screen-3| is supported and guided in itsinclined relation'by a plurality of rollers 35, 35 andis vibrated backand'iorth by a power-driven eccentric 36 connected to the underside ofthe delivery chute 31 of the screen by a connecting-rod 38, there beingnothing novel in the particular mechanism for actuating this screen. a

The rotary, multiple drum |2-'-|3--|4 is housed in a casing 39 throughthe opposite end walls of which'the chute 28 and the screen 3| project,such casing having a bottom 4| converging downwardly to a centraldischarge-pipe 42 through which the material passing through the outerof the three screens passes, such pipe being connected to a side-flue 43joined to a combustiontube 44 equipped with an oil-burner45, fine 43,having damper-equipped openings or vents 46 by means of which the amountoi entering outer air may be readily regulated to control thetemperature of the drying gases constituting the products of combustionfrom the burner.

As will be readily understood,"the hot gases flow through conduits 44,43, 42 into the main housing or shell 38, and after properly drying thecontents of the revolving screens pass out through the chute 28.

At its lower end the appliance has a chute 41 for the dischargetherethrough of the cleaned, sized vermiculite which is deliveredthereto in any approved manner from the outer screen |4 through themeshes of which it does not pass.

Assuming that the multiple-screen |2-|3-|4 is rotating at an appropriatespeed, that the vibratory or reciprocatory screen 3| is working, andthat the hot gases are at a suitable temperature and flowing through theapparatus, the operation of the appliance is substantially as follows:

The impure ore as it comes from the mine is passed through athree-quarter-inch revolving grizzle to eliminate the larger pieces ofimpurities and it then enters the revolving multiple-drum through theinclined chute 28.

In the innermost of the three drums, the lumps or conglomerates ofimpurities and vermiculite are shattered, the larger pieces or boo ofvermiculite are flaked, and the bigger pieces of impurities are brokenup or disintegrated by the action of the metal grinding-rods IS.

The rotation of such inner drum and the more or less flightlikeconstruction of the bars l5 which it is composed lift up the particlesremaining in the drum and drop them onto the reciprocating screen 3|,which removes the larger impurities and permits the vermiculite and thesmaller pieces of impurities to pass through and onto the grinding-rodsagain.

The slots of such vibrating screen are of such width. as to allow thevermiculite to pass therethrough edgewise, but the larger pieces ofimpurities are retained on the screen and are removed by sliding downthe bars of which the screen is made and delivered at the outer end ofthe screen structure exterior to the drum housin or casing.

As has been indicated, the spacing of the reciprocating-screen bars issuch that they are closer together the farther away from the entrancechute 28, because the vermiculite flakes are thinner and the impuritiesare smaller as they proceed down the screen due to their being subjectedto more grinding action by the rods i6.

Flakes of vermiculite and particles of impurities that are ofsufliciently small size pass through the openings .of the intermediateslotted screen l3 and onto-the square-opening screen l4.

Flakes thatare larger than .078 inch square in area will be retained onand delivered Irom screenl4, while all impurities and flakes that areunder .078 inch ,will pass through such outer screen 'and be deliveredthrough the conduit 42.

Practically all of the impurities will pass through the square-openingscreen, 42 because they arev more or less round or cubical in shape, andthose that have passed through the middle screen with its .04 inch slotswill pass through the .078 inch square openings.

Only a few of the impuritiesare flatand are retained on thesquare-opening or flnal screen, whereas the vermiculite being iiat andthin will readily pass through the narrow slots of the middle screen,but those particles having an area greater than .078 inch will not passthrough the square apertures of the outer screen.

The clean vermiculite passes through the exit 4l and the portion passingthrough the squareopening screen l4 drops through the duct 42 intoanother apparatus constructed according to the same principle but withdifferent dimensions so as to operate on smaller sizes, or it is cleanedby other means that are adapted to act on small sizes of vermiculiteore.

Various modifications of the above process and apparatus in someinstances can be used to advantage; for example, the mine-runore whichhas first passed through a three-quarter-inch grizzle to removelarge-pieces can then be treated in an apparatus similar to thatillustrated and described with the exception that no breaking orgrinding rods l6 are employed and no vibratory screen 3| is used insideoi the drums, the purpose of such an apparatus being to separate theparticles of impurities and vermiculite which are originally of a sizethat, would pass through the openings of the several drums, which actiondecreases the chance of these particles being unnecessarilydisintegrated in the regular apparatus with the grinding-rods and itreduces operating costs by avoiding the necessity of turning over therods for dsintegrating purposes when screening only is required. Theemployment of such a device also facilitates grinding of the impuritiesand flaking of the vermiculite in the regular apparatus, as there is nobuffing effect due to the fines.

It is considered as a valuable part of this invention that vermiculiteflakes can be split into thinner ones when subjected to a shearing forceparallel to the planes of the flakes and that this splitting is greatlyimproved by moistening the vermiculite particles, and in this connectionit is to be remembered that besides vermiculite, this principle can beapplied to any cleaning problem in which flake-like particles are to besegregated from round or cubical particles of a friable nature.

As has been indicated, the larger pieces which do not as first passthrough the inner drum, as well as those remaining on the middle. drum,are carried up by the rotation of the drums and dropped onto thereciprocating screen and those particles which pass through the latterdrop onto the lower part of the inner drum and are again acted upon bythe grinding-rods, this action occurring repeatedly if necessary.

are subject to modification without departure from the principles onwhich the invention is based.

I claim:

1. In an appliance for separating of the vermiculite group from itsimpuritiea the combination of a'rotary trornmel having threescreen-drums one inside of the other, means to rotate saidtrommel,"means to introduce the impure 'ore .to be treated into theinnermost of said screen-drums, said innermost screen-drum having slotsapproximately three-quarters ofan inch wide,.the intermediatescreen-drum having slots approximately four one-hun'dredths of i an inchin width, the third outer 'screemdrum having substantially-squareopenings practically seventy-eight one-thousandths of an inch on a side,free elongated grinding-rodsin and lengthwise of said innermost drum toapply a shearing force to the vermiculite particles substantiallyparallel to the planes of the flakes of which they are composed todivide such particles into thinner particles and to break up theimpurities into smaller pieces, an inclined reciprocatory screeninsideof said trommel having a plurality of sections with difierentsizes 'of screen openings and located to receive the material carriedupby, and delivered to it by,the rotary trommel and to discharge thematerial which does not pass through the screen outside of said trommel,and means to deliver the segregated treated'vermiculite and thefragmerited impurities separately from the appliance.

2. In an apparatus for separating'amineral of the vermiculite'group fromits impurities, the combination of a rotary'trommel having threescreen-drums inside of and spaced from one another, said innermostscreen-drum having longitudinal slots, said intermediatescreen-drumhaving narrower longitudinal slots, said outer screendrumhaving apertures each with its two dimensions substantially equal, andwith such dimension greater than the width of the slots in theintermediate screen-drum, means to rotate said trommel, means tointroduce the impure ore to be treated into said innermost screen-drum,a plurality of free elongated grinding-rods in and disposed lengthwiseof said innermost screendrum to apply shearing forces tothe vermiculiteparticles therein substantially parallel to the planes of cleavage ofthe flakes .0! which they a mineral The invention is defined by theappended are composed to divide such particles into thinner flakes andto break up the impurities into smaller pieces, means to deliver thevermiculite particles .which fail to pass through said outerscreen-drum, and means to separately discharge the impurity particleswhich pass through said outer screen-drum.

3. The structure presented in claim 2 in combination with means to heatthe material undergoing treatment in the appliance. I

4. The structure presentedin claim 2 in which the slotsin'said'innermost screen-drum flare outwardly and are oblique to theircorresponding radii 1 i 5. In an apparatusior-separating a mineral ofthe vermiculite group from its impurities, the combination ofa rotarytrommel having three screendrums inside of and spaced from one another,said innermost screen-drum having longitudinal s1ots, said intermediatescreen-drum having narrower longitudinal slots, said outer screen-drumhaving apertures each with its two dimensions substantiallyequal, meansto rotate said trommel, means to introduce the impure ore tobetreatedinto said innermost screen-drum, a reciprocatoryscreen insideof said innermost screen-drum to receive the material carried up by, anddropped into it during the rotation of,

the 'trommel and to deliver its portion retained on the screen outsideof the trommel, a plurality of free elongated grinding-rods in anddisposed lengthwise of said innermost screen-drum to apply shearingforces to the vermiculite particles therein substantially parallel tothe planes of cleavage of the flakes of which they are composed todividesuch particles into thinner flakes and to break up the impuritiesinto smaller pieces, means to deliver the vermiculite particles whichfail to pass through said outer screen drum,

andmeans to separately discharge the impurity particles which passthrough said outer screendrurn.

6. The structure presented in claim 5 in which the reciprocatory. screenis inclined and has a plurality of sections with different sizes ofscreen openings.

7. The structure presented in claim 1, in which the slots of saidinnermost screen-drum flare outwardly and are oblique to theircorresponding radii.

RICHARD ERICSON.

